This is a request for continuation of the joint training program in psychiatric epidemiology and biostatistics at the Harvard School of Public Health. The principal objectives of the training program are to educate promising predoctoral and postdoctoral students to become epidemiological and biostatistical scientists in psychiatric research. A total of eleven predoctoral and five postdoctoral trainees are requested. Rapid developments in the basic sciences of epidemiology and biostatistics provide opportunities for pushing further the frontiers of research in psychiatric disorders, in understanding the natural history, genetic and environmental risk factors, and developing better treatment and prevention strategies. There exists a critical need for high level technical training in the companion core disciplines of epidemiology and biostatistics. The Departments of Epidemiology and Biostatistics at HSPH are noted world wide as leading centers for training in biostatistics and epidemiology. We have the commitment of an accomplished training faculty from the Departments of Epidemiology (8 faculty), Biostatistics (13 faculty) and affiliated departments at Harvard (14 faculty) with focal emphasis on: 1) preventive research; 2) psychiatric genetic epidemiology; and 3) clinical trials. Our joint training program, initiated in 1991, has rapidly expanded and flourished over the past nine years. Both departments have a strong record of producing high quality trainees. Doctoral trainees typically take two full years of coursework, with a concentration either in biostatistics or epidemiology, and often a minor concentration in the other field. Doctoral students must pass a written and oral qualifying exam, usually by the third year of doctoral studies. Upon completion of the oral exam, a research committee is formed of three faculty, generally with at least one faculty member from biostatistics and one from epidemiology. The postdoctoral training program in epidemiology offers degree training to psychiatrists wishing to specialize in epidemiologic research; both departments offer non-degree postdoctoral training for Ph.D.?s or Sc.D.?s with a solid training in epidemiology, biostatistics or a related field who wish to specialize in mental health.